Talk:Paper - Some Observations on the Development of the Ventral Pancreas in Man

An Early Human Ovum (Thomson) in situ. Odgers PN. J Anat. 1937 Jan;71(Pt 2):161-168.3. No abstract available. PMID 17104634

An Early Human Ovum (Thomson) in situ

IN March 1913 the late Prof. Arthur Thomson received the uterus, which contained this ovum, with its adnexa from Prof. H. M. Turnbull of the LondonHospital. HebrieflydemonstratedittotheAnatomicalSectionofthe XVIIth International Congress of Medicine, which was held in London in the summer of that same year, but he never published any detailed description ofit.Somefiveyearsagohesuggestedtome thatitwaswellworthfurther examination,butitwasnotuntilafterhisdeaththattheslidesofthisspecimen with his serial microphotographs and notes about it were brought to my notice. Ishallcallitinthispaperafterhisname,andIhopethat,ifitisever referred to in the future, itmay be known as the Thomson ovum.

Prof. Turnbull discovered it in the decidua of the posterior wall of the uterus of an unmarried woman, aged 20, who died 5 hours after severe burns on 4 March 1913. The right ovary contained a corpus luteum, which measured 24*5x17-5mm. The woman's menstrual history was as follows. It first occurred at 15 years of age and had always been regular. Her last period commenced on3February,exactly29 daysbeforeherdeath. No datesofcoitus were available. The post-mortem examination took place 26 hours after death. The specimen was fixed in 10 per cent. formalin and cut into sections 10 thick.

From the menstrual history the maximal age of this ovum must be about 16 days. The inside measurements of the blastocyst are 2-1x 151 x 0-7 mm.; theembryonicdiscmeasures0-26x0-31(?)x0-16mm. (?).

In the following list it is placed among its contemporaries. DrS.Zuckerman has kindly computed for me from the inside measurements of the blastocyst cavity a rough estimate of its cubic capacity in the several ova, the cavities beingregardedforthispurposeasperfectspheres,ofwhichthediameterswere taken as the mean of the dimensions given. These figures are added in a separate column.

As is seen in the general view (PI. I, fig. 1), the blastocyst cavity and the trophoblast are well preserved, but the embryonic disc, particularly the ectoderm, has suffered a good deal of disorganization, the amniotic cavity being partly obscured by cellular detritus. While this forbids any detailed description of the disc itself, I wish to draw attention here to:

1. the formation of the extra-embryonic coelom, and
2. the wall of the yolk sac.

I. THE EXTRA-EMBRYONIC COELOM

On either side of the amnio-embryonic vesicle a space is seen (P1. I, fig. 2), the one on the left being triangular in section, while the right one appears more quadrangular in shape. These are marked off from the rest of the blastocyst cavity by a regular layer - of mesothelial cels, which vary in differentsectionsintheirnumberandtheir shape, most of them being round, while aminorityareflatterandspindle-shaped. They are partially filed by coagulum similar to thatofthemagma. Ifthealmostsymmetricalchannelsthus formed are traced in one direction, they areseentocoalesceand surroundthisendoftheembryonicdisc(PI.I,fig.1), the common channel extending for thirteen sections beyond the disc: traced in the opposite direction they are observed to narrow and finallydisappear, the right before the left, sixteen sections from the disc, but here they are always separated from each other by a strand of mesenchyme and never join (PI.I,fig.4).